A building BLOCK approach to bis-porphyrin cavity systems with convergent and divergent wall orientations

Article abstract of DOI:10.1016/S0040-4020(02)00174-6

Porphyrin containing molecular building blocks have been linked together using s-tetrazine or 1,3-dipolar coupling protocols to yield bis-porphyrin cavities of defined shape and size which were evaluated by molecular modelling.

Full text of DOI:10.1016/S0040-4020(02)00174-6

TETRAHEDRON
Pergamon
Tetrahedron 58 72002) 3445±3451
A building BLOCK approach to bis-porphyrin cavity systems
with convergent and divergent wall orientations
Martin R. Johnston,a,p Maxwell J. Gunterb and Ronald N. Warrenera
aCentre for Molecular Architecture, Central Queensland University, Rockhampton, Qld 4700, Australia
bDepartment of Chemistry, University of NewEngland, Armidale, NSW 2351, Australia
Received 22 August 2001; revised 21 January2002; accepted 14 February2002
AbstractÐPorphyrin containing molecular building blocks have been linked together using s-tetrazine or 1,3-dipolar coupling protocols to
yield bis-porphyrin cavities of de®ned shape and size which were evaluated by molecular modelling. q 2002 Elsevier Science Ltd. All rights
reserved.
1. Introduction
molecular `universal joint' containing two units of zinc
metallated 1 co-ordinated with a tetra74-pyridyl) ligand.10
We have subsequentlyapplied the coupling technique used
to prepare 1 to other porphyrin BLOCKs to create a variety
of bis-porphyrin molecules.11
The construction of arti®cial photosynthetic systems
utilising the porphyrin macrocycle to mimic the natural
bacteriochlorophyll chromophore is an area of ongoing
activity.1 This has resulted in the synthesis of numerous
architectures in which the porphyrin macrocycle has been
speci®callypositioned covalentlywithin an array. Several
recent examples from the literature include porphyrin
wheels,2 wires,3 windmills,4 squares,5 rotaxanes,6 and even
structures containing up to 128 porphyrin rings.7
In this studywe demonstrate further the potential of the
block building concept using components with differing
geometries. In particular, we use norbornene components
with acute-angled attachments of porphyrin effectors,
speci®cially 2, 3 and 4, and link them with spacer bis-
epoxide units 6 and 7 that contain a curved or rod-like
topology, respectively 7Fig. 2) or with the s-tetrazine
reagent 5. Two different assemblyprotocols have been
selected, one based on Diels±Alder cycloaddition
chemistry,12 the other employing 1,3-dipolar cycloaddition
reactions.13 Porphyrin BLOCKs 39 and 414 and coupling
reagents 5,11 6,15 and 716 have been reported previously,
whereas the synthesis of BLOCK 2 is reported for the ®rst
time.
The controlled positioning of the porphyrin ring within
designed architectures has also seen application in the
synthesis of host systems, particularly exempli®ed in bis-
porphyrinic structures.8 We have reported the synthesis of
the V-shaped bis-porphyrin 1 7Fig. 1) using BLOCK
coupling techniques,9 and examined its abilityto form
complexes with appropriately sized dipyridyl functionalised
guests. This concept was exploited in the formation of a
Figure 1. The overall V-shape of bis-porphyrinic host 1 revealed byan AM1 minimised structure. Metallated 1 is capable of forming complexes with suitably
sized and functionalised guests.
Keywords: cycloadditions; porphyrins and analogues; host compounds; molecular modelling.
Corresponding author. Present address: School of Chemistry, Physics and Earth Sciences, Flinders University, Bedford Park, Adelaide, SA 5042, Australia.
Tel.: 161-8-820-12317; fax: 161-820-12905; e-mail: martin.johnston@¯inders.edu.au
p
0040±4020/02/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020702)00174-6

3446
M. R. Johnston et al. / Tetrahedron 58 /2002) 3445±3451
Figure 2. Norbornenyl functionalised porphyrin BLOCKs 2±4 and the coupling reagents 5±7 used to produce bis-porphyrin cavities. The designated angles
represent the position of the porphyrin plane relative to a plane containing the ethano and etheno carbon atoms of the terminal norbornene.
The topological contribution made bythe spacer units is
important to the overall geometryof the ®nal product.
Coupling with bis-epoxide 6 produces a polynorbornane
frame which is distinctlycurved, whereas introduction of
a s-bond between the bridges of the two central nor-
bornanes creates a polynorbornane that is signi®cantly
straightened, and this is achieved byemploying bis-epoxide
7. The immediate outcome is that cavitysytems
constructed from BLOCKs 2, 3 and 4 with bis-epoxide 7
will have the cavitywalls more obliquelyangled than those
formed using bis-epoxide 6, irrespective of which alkene
block is used in the assemblyprotocol.
2.17) and Hb 7d 1.48) signals in 11 that have been shifted
up®eld by0.65 and 1.14 ppm, respectively, from those in 2
bythe proximityof the azo-bridge of the diaza-
bicyclo[2.2.2]octene ring system and served to con®rm the
geometryshown. Further evidence for the structure of 11
was obtained from high resolution electrospraymass spec-
troscopyin which a doublycharged doublyprotonated
molecular ion {7M12H)21 1386.861} was observed.
Reaction of BLOCK 2 with bis-epoxide 6 under ACE
coupling conditions 71608C, DCM) produced the cavity
molecule 12 in good yield 767%) 7Scheme 1). The reaction
is presumed to proceed via a 1,3-dipolar intermediate
formed after ring-opening of the cyclobutane epoxide
rings of 6. In conjunction with the expected loss of the
ole®nic proton resonance of 2, the characteristic chemical
shifts were observed for the protons Ha 7d 3.15) and Hb 7d
1.71) upon formation of the bis-porphyrin cavity 12. In
particular, Ha is in¯uenced bythe close proximityof the
oxygen atom in the adjacent norbornane ring and is shifted
down®eld by0.33 ppm 7relative to 2), which supports the
exo,exo-geometryof the coupled product. Electrospray
mass spectrometry7dichloromethane/formic acid solutions)
indicated the doublycharged, doublyprotonated molecular
ion {7M12H)21 1486.871} consistent with structure 12 was
present.
Molecular modelling17 has been used to evaluate the size
and shape of the resulting bis-porphyrin cavities 7Scheme 3)
and reveals a large range of both inter-porphyrin angles
Ê
742±938) and separation distances 710±32 A).
2. Results
The synthesis of porphyrin BLOCK 2 is outlined in
Scheme 1. The known a-dione 9 was prepared in situ by
hydrolysis of the dichloride precursor 818 and condensed
with Crossley's porphyrin diamine 108f,19 to produce the
porphyrin building BLOCK 2. The porphyrin is rigidly
connected to the norbornenyl ring by the intervening planar
tetraazaanthracene heteroaromatic rings. The geometryof
BLOCK 2 was established bymolecular modelling which
showed that the porphyrin was positioned at an angle of 338
relative to the plane formed bythe four base carbons of the
norbornyl unit. The geometry of 2 complements that in
BLOCKs 3 and 4 7Fig. 2) which displayincreasinglylarger
angles of 43 and 898, respectively.
In a similar manner, treatment of BLOCK 2 with the bis-
epoxide 7 yielded the bis-porphyrin cavity 13 7Scheme 1),
and shifts for the proton resonances originating from the
porphyrin BLOCK were again observed. By analogy with
11 and 12, the protons Ha and Hb of 13 were shifted to d 3.17
and 1.75, respectively, con®rming the extended geometry of
the alicyclic backbone. In addition, two sets of ester
resonances 7ratio 2:1) were observed 7d 4.03, 3.55) corre-
sponding to those attached to the 7-oxanorbornane rings and
the central dihydrosesquinorbornane unit, respectively.
Electrospraymass spectrometrywas again con®rmatory,
with a doublycharged doublyprotonated molecular ion at
{7M1H)21 1577}.
The methods used to incorporate porphyrin BLOCK 2 into
the bis-porphyrin cavities 11±13 are outlined in Scheme 1.
The reaction of s-tetrazine 5 with norbornene BLOCK 2 was
carried out under high pressure conditions 714 kbar, 4 days)
in dichloromethane and yielded the bis-porphyrin cavity 11
in good yield 757%). The bis-porphyrin 11 was isolated
from the reaction mixture using column chromatography
Having successfullyisolated bis-porphyrins based on the
coupling of BLOCK 2, attention was directed to BLOCK
3. Thus, treatment of BLOCK 3 with the s-tetrazine 5 or the
epoxide reagents 6 and 7 yielded bis-porphyrin cavities 1,
14 and 15, respectively7Scheme 2). The structurally
diagnostic NMR shifts for resonances for protons Ha and
1
7silica gel) and characterised by H NMR spectroscopy
and mass spectrometry. The C2V symmetry of 11 simpli®ed
1
the H NMR spectrum and reinforced the stereoselective
nature of the coupling reaction. Characteristic proton reso-
nances were observed for the methano bridge protons Ha 7d

M. R. Johnston et al. / Tetrahedron 58 /2002) 3445±3451
3447
Scheme 1. Synthesis of porphyrin building BLOCK 2 and its subsequent coupling to produce bis-porphyrin cavities 11±13.
Hb were again observed in these bis-porphyrin cavities. In
the case of BLOCK 3, the proximityof the bicyclo[2.2.2]-
octene double bond to the methano bridge selectivelyaffects
the resonance of Hb 7d 2.84) whereas the resonance for Ha is
observed in the usual position 7d 1.23). However, the
coupling of BLOCK 3 places Ha into the shielding region
of either the diazabicyclo[2.2.2]octene subunit in 1, or the
deshielding region of the 7-oxanorbornane in the case of 14
and 15, resulting in the resonance for Ha being observed at d
0.8 for 1 and 1.85 in 14. A similar situation is observed for
the resonance of Hb which resonated at 1.79 and 2.10 for 1
and 14, respectively. In the case of 15, the resonances for Ha
and Hb cannot be unambigiouslyassigned due to the
coincidence of signals from protons endo to the rack back-
bone. All bis-porphyrin materials formed from the coupling
of BLOCK 3 gave satisfactorymass spectroscopic results.
In the case of BLOCK 4, molecular modelling predicted that
Scheme 2. Bis-porphyrin cavities produced from the coupling of BLOCK 3 and 4 with various spacer units.

3448
M. R. Johnston et al. / Tetrahedron 58 /2002) 3445±3451
Scheme 3. Molecular modelling of the various bis-porphyrin cavities 11±16.
the targeted bis-porphyrin products formed utilising s-tetra-
zine 5 or bis-epoxide 6 as coupling reagents would be
extremelystericallycrowded. The curved nature of the
alicyclic backbone produced using these coupling reactions,
in conjunction with the acute angle of the porphyrin relative
to the norbornene ring within BLOCK 4, combine to
produce bis-porphyrin cavities for which modelling indi-
cated that the porphyrin moieties would actually cross
over each other underneath the backbone, hence these
couplings were not investigated. However, reaction of 4
with bis-epoxide 7 was conducted and found to produce
the convergent walled cavity 16. Byanalogywith the
previous systems, the methano bridge proton resonances
were assigned Ha 7d 2.75, Dd 10.87) and Hb 7d 1.56, Dd
20.32) in line with their proximityto the adjacent 7-oxanor-
bornane. In a similar fashion to 15, two ester resonances
7ratio 2:1) were observed 7d 3.24, 3.88) con®rming the
presence of the spacer 7 and the 7-oxanorbornane rings
produced as a result of the epoxide coupling protocol.
level and the results are shown in Scheme 3. The models
reveal the overall V-shape of the cavities, which are
characterised byan inter-porphyrin angle and a porphyrin
centre-to-centre distance, 7Scheme 3).
These data reveal a range of bis-porphyrin cavities with
Ê
inter-porphyrin separations ranging from 10.7 A in 16 to
Ê
32 A in 15. The angles subtended bythe porphyrin rings
within the cavities varyfrom 42 8 in 14 to 938 in 13. In the
case of 16, the porphyrin rings are convergent at the base of
the cavity, in complete contrast to all the other cavities
synthesised in which the porphyrins are divergent.
4. Conclusion
In conclusion, we have demonstrated that the utilisation of
porphyrin bearing building BLOCKs in combination with
various coupling reagents is an ef®cient means of cavity
construction. The geometric variations between the
porphyrin BLOCKs readily facilitates the construction of
cavities with different centre-to-centre distances and angles
subtended between the porphyrin macrocycles. Metallated
derivatives of these cavities are currentlybeing investigated
in host/guest and photochemical studies.
3. Molecular modelling
Molecular modelling has been used as a tool to evaluate the
size and geometryof the bis-porphryin cavities. The
modelling was carried out at the semi-empirical 7AM1)

M. R. Johnston et al. / Tetrahedron 58 /2002) 3445±3451
3449
5. Experimental
139.79, 140.75, 141.06, 141.71, 145.64, 148.83, 149.03,
153.58, 154.94, 166.29.
5.1. General
5.1.2. Bis-porphyrin cavity 11. Porphyrin BLOCK 2
740 mg, 31 mmol) and s-tetrazine 5 74 mg, 17 mmol) were
dissolved in DCM 7300 ml) containing triethylamine 730 ml)
and the solution pressurised at 14 kBar for 4 days. The
solution was diluted with CHCl3, washed with HCl 71 M),
water, NaHCO3 solution, water and dried 7Na2SO4). Puri®-
cation was achieved using column chromatography 0silica)
eluting with DCM followed byCHCl 3/THF 71%) to give 11
718 mg, 57%). Mp.3508C, HR-ESMS: C190H208N20
7M12H)21 expected 1386.856, found 1386.861. UV
7DCM) l, 71£103): 424 7332.4), 465 7144.6), 534 723.2),
567sh 711.4), 607 716.1), 658 74.9). IR 7KBr): 2957.2 7t-Bu
C±H stretch), 1654.3, 1591.9 7Ar skeletal), 1466.0 7CH2
deformation), 1363.6 7t-Bu C±H deformation), 1246.3
7t-Bu skeletal), 802.0 7Ar-H, 2 adjacent H).
All solvents were used as supplied with the exception of
THF 7distilled from Na/benzophenone); pyridine 7distilled
from KOH and stored over molecular sieves). Melting
points were determined using a Gallenkamp melting point
apparatus and are uncorrected. Thin layer chromatography
7TLC) was performed on Merck silica gel 60 pre-coated
aluminium sheets and visualised using visible or UV light
7254 and 365 nm). Column chromatographywas carried out
under a positive air pressure using Merck silica gel
7230±400 mesh). NMR spectra were acquired on either a
Bruker AMX300 7300 MHz) or Bruker DRX400
7400 MHz) using standard Bruker pulse programs. Unless
otherwise stated, spectra were recorded at 303 K using
deuterated CHCl3 as the solvent with tetramethylsilane
7TMS) as the internal standard. Chemical shifts 7d) are
reported as parts per million 7ppm) with respect to TMS.
Mass spectra 7MS) were analysed on Micromass Mass
Spectrometer using electron impact 7EI) or electrospray
7ES) techniques for larger bis-porphyrin systems. MALDI-
TOF mass spectroscopywas also necessaryin some
cases.
1H NMR 7CDCl3): d 22.46 74H, bs); 1.48 7hidden, 2H, d,
Jˆ10.8 Hz); 1.41±1.54 7144H, m); 2.15 72H, d,
Jˆ10.8 Hz); 3.24 74H, s); 3.28 74H, s); 7.59±7.63 72H,
m); 7.77 74H, t, Jˆ1.7 Hz); 7.88 74H, t, Jˆ1.7 Hz); 7.91
74H, s); 7.97 74H, s); 8.04 74H, d, Jˆ1.7 Hz); 8.05 74H, d,
Jˆ1.7 Hz); 8.14 72H, t of d, Jˆ1.7, 7.7 Hz); 8.44 74H, s);
8.72 74H, s); 8.91 74H, d, Jˆ5 Hz); 8.94 74H, d, Jˆ5 Hz);
8.98 72H, bs); 9.10 72H, d, Jˆ4 Hz). 13C NMR: 31.71,
31.84, 31.91, 34.96, 35.02, 38.89, 47.34, 49.06, 117.95,
120.52, 121.10, 122.96, 123.23, 128.00, 128.35, 128.62,
129.37, 129.48, 129.64, 130.89, 134.89, 134.15, 137.0,
138.06, 139.5, 139.6, 139.8, 140.7, 141.0, 145.4, 148.8,
148.92, 149.03, 151.54, 153.79, 154.92, 159.00, 163.88.
Porphyrin BLOCKs 3 and 4 were prepared as previously
reported. Professor D. N. Butler is thanked for a gift of
dichloride precursor 8, and Dr Davor Margetic for the
provision of bis-epoxides 6 and 7.
5.1.1. Porphyrin BLOCK 2. Dichloride precursor 8
721 mg, 95 mmol) was dissolved in dioxane/water 73 ml,
1:1) and the solution heated under re¯ux in an N2
atmosphere for 3 h. Upon cooling, the solution was diluted
with water 730 ml) and extracted with DCM 73£30 ml). The
combined organic material dried 7Na2SO4) and concentrated
to a yellow oil.
5.1.3. Bis-porphyrin cavity 12. Porphyrin BLOCK 2
79 mg, 7 mmol) and bis-epoxide 6 72 mg, 5 mmol) were
dissolved in CD2Cl2 7350 ml) and heated at 1608C in a
sealed NMR tube for 48 h. The crude reaction mixture
was puri®ed bycolumn chromatography7silica) eluting
with DCM/petroleum spirit 71:1) followed byCHCl
/
3
EtOAc 75%) to give 12 as a purple solid 77 mg, 67%).
Mp.3508C, HR-ESMS: C197H220N16O10 7M12H)21
expected 1486.871, found 1486.871. UV 7DCM) l,
71£103): 423 7459.2), 462 799.4), 537 723.5), 571sh
712.5), 609 718.7), 658 74.1), 701 71.4). IR 7KBr): 2959.9
7t-Bu C±H stretch), 1734 7CvO stretch), 1592.0 7Ar
skeletal), 1474.3 7C±H deformation, Ar skeletal), 1362.1
7t-Bu C±H deformation), 1287.8, 1245.7 7t-Bu skeletal),
1092.9 7C±O stretch), 800.0 7Ar-H, 2 adjacent H).
Diaminoporphyrin 10 721 mg, 18 mmol) was dissolved in
DCM 72 ml) and added to the above material and the result-
ing solution stirred under N2 atmosphere in the dark for
24 h. The reaction product was puri®ed bycolumn chroma-
tography7silica) eluting with DCM/petroleum spirit 71:1) to
yield 2 as a purple solid 713 mg, 60%). Mp.3508C, MS
7M1H)1 1292.9. UV 7DCM) l, 71£103): 423 7238.9),
452sh 775.7), 535 715.6), 568sh 76.7), 606 711.8), 656
71.7). IR 7KBr): 2959.2 7t-Bu C±H stretch), 2866.6 7CH
C±H stretch), 1592.0 7Ar skeletal), 1474.5, 1458.2 7C±H
deformation, Ar skeletal, CH2 deformation), 1362.2 7t-Bu
C±H deformation), 1285.4, 1232.3 7t-Bu skeletal), 879.4
7Ar C±H out-of-plane), 801.4 7Ar-H, 2 adjacent H), 710.5
7cis-CHvCH, C±H stretch).
1H NMR 7CDCl3): d 22.44 74H, bs); 1.46±1.50 7144H, m);
1.71 72H, d, Jˆ10 Hz); 1.96 74H, s); 2.02 72H, s); 2.21 72H,
s); 2.49 74H, s); 3.15 72H, s, Jˆ10 Hz); 3.52 74H, s); 4.00
712H, s); 7.77 74H, t, Jˆ1.7 Hz); 7.90 74H, t, Jˆ1.7 Hz);
7.93 74H, s); 7.97 74H, s); 8.05 78H, t, Jˆ1.7 Hz); 8.50 74H,
s); 8.73 74H, s); 8.93 74H, d, Jˆ5 Hz); 8.97 74H, d, Jˆ5 Hz).
13C NMR: 31.71, 31.88, 35.02, 38.20, 46.69, 52.70, 52.88,
55.02, 65.56, 90.09, 117.95, 120.63, 121.15, 123.06, 128.08,
128.37, 128.60, 128.84, 129.38, 129.48, 130.89, 134.23,
138.12, 139.52, 139.75, 139.77, 140.68, 140.97, 148.83,
149.02, 149.06, 153.86, 155.01, 163.27, 168.37.
1H NMR 7CDCl3): d 22.40 72H, bs); 1.52 772H, s); 2.62
71H, d, Jˆ9 Hz); 2.82 71H, d, Jˆ9 Hz); 4.07 72H, t,
Jˆ1.8 Hz); 6.91 72H, 2H, t, Jˆ1.8 Hz); 7.81 72H, t,
Jˆ1.2 Hz); 7.96 72H, t, Jˆ1.2 Hz); 8.02 74H, m); 8.12
74H, d, Jˆ3 Hz); 8.45 72H, s); 8.79 72H, s); 8.99 72H, d,
Jˆ6 Hz); 9.04 72H, d, Jˆ6 Hz). 13C NMR: 29 out of 30
resonances seen; 31.73, 31.91, 35.04, 49.37, 60.12,
118.00, 120.67, 121.12, 122.95, 128.03, 128.33, 128.54,
128.60, 128.79, 129.52, 134.18, 138.09, 138.46, 139.69,
5.1.4. Bis-porphyrin cavity 13. Porphyrin BLOCK 2
711 mg, 8.6 mmol) and bis-epoxide 7 72 mg, 3.4 mmol)

3450
M. R. Johnston et al. / Tetrahedron 58 /2002) 3445±3451
were dissolved in CD2Cl2 7300 ml) and the solution heated at
1408C for 2 days, followed by 1608C for 2 days. The solu-
tion was taken to dryness and the reaction mixture puri®ed
bycolumn chromatography7silica) eluting with DCM/
5.1.7. Bis-porphyrin cavity 16. Porphyrin BLOCK 4
720 mg, 14 mmol) and bis-epoxide 7 74 mg, 6.8 mmol)
were dissolved in CD2Cl2 7350 ml) and heated to 1408C in
a sealed NMR tube for 4 days. The product was puri®ed by
column chromatography7silica) eluting with DCM/
petroleum spirit 71:1) followed byCHCl /EtOAc 75%) to
3
yield 13 710 mg, quantitative). Mp.3508C, ES-MS
petroleum spirit 71:1) followed byCHCl /EtOAc 75%) to
3
C206H228N16O14 M21 1576, MS 7M1H)21 1577.
give 16 719 mg, quantitative). This was recrystallised
from DCM/MeOH. Mp.3508C. MALDI-TOF MS
C230H240N16O14 expected 3452.4, seen 3452.6. UV 7DCM)
l: 364, 430, 532, 612, 661. IR 7KBr): 2951.6 7t-Bu C±H
stretch), 2860.7 7CH C±H stretch), 1734.1 7CvO stretch),
1591.5 7Ar skeletal), 1474.1, 1457.9, 1348.6 7C±H
deformation, Ar skeletal, CH2 deformation), 1362.1 7t-Bu
C±H deformation), 1287.3, 1247.1 7t-Bu skeletal), 1089.2
7C±O stretch), 880.5 7Ar C±H out-of-plane), 800.0 7Ar-H, 2
adjacent H).
1H NMR 7CDCl3): d 22.40 74H, bs); 1.48±1.56 7144H, m);
1.75 72H, d, Jˆ10 Hz); 2.27 74H, s); 2.64 74H, s); 2.76 74H,
s); 2.94 72H, s); 3.19 72H, d, Jˆ10 Hz); 3.54 74H, s); 3.56
76H, s); 4.04 712H, s); 7.79 74H, t, Jˆ1.7 Hz); 7.93 74H, t,
Jˆ1.7 Hz); 7.99 78H, d, Jˆ1.7 Hz); 8.08 78H, d, Jˆ1.7 Hz);
8.52 74H, s); 8.76 74H, s); 8.96 74H, d, Jˆ5 Hz); 9.00 74H, d,
Jˆ5 Hz).
5.1.5. Bis-porphyrin cavity 14. Porphyrin block 3 750 mg,
36 mmol) and bis-epoxide 6 76 mg, 1.5 mmol) were
dissolved in CD2Cl2 7400 ml) and heated at 1608C for 9
days in a sealed NMR tube after which time no starting
material remained. The reaction mixture was subject to
1H NMR 7CDCl3): d 22.50 74H, bs); 1.39 736H, s); 1.43
736H, s); 1.51 772H,s); 1.56 hidden 72H, d, Jˆ8.5 Hz); 1.58
74H, s); 1.88 74H, s); 2.10 74H, s); 2.58 74H, s); 2.71 72H, s);
2.75 72H, d, Jˆ8.5 Hz); 3.24 76H, s); 3.88 712H, s); 4.10
74H, s); 7.57 74H, d, Jˆ7 Hz); 7.75 74H, t, Jˆ1.7 Hz); 7.87
74H, bs); 7.90 74H, t, Jˆ1.7 Hz); 7.97 78H, bs); 8.03 74H,
bs); 8.44 74H, d, Jˆ7 Hz); 8.68 74H, s); 8.70 74H, s); 8.87
78H, m).
column chromatography7silica) eluting with CHCl
give 14 as a purple solid 713 mg, 23%). Recrystallised
to
3
from
DCM/MeOH,
mp.3508C.
HR-ESMS:
C209H234N16O10 7M12H)21 expected 1564.927, found
1564.927. UV 7DCM) l, 71£103): 424 7327.2), 457sh
7103.2), 537 727.4), 570sh 713.5), 609 722.9), 658 73.9).
Acknowledgements
1H NMR 7CDCl3): d 22.44 74H, bs); 1.54±1.46 7144H, m);
1.96±1.85 722H, m); 2.11 72H, d, Jˆ9 Hz); 2.35 74H, s);
3.88 712H, s); 4.24 74H, t, Jˆ4 Hz); 6.51 74H, t, Jˆ4 Hz);
7.77 74H, t, Jˆ1.7 Hz); 7.91±7.96 712H, m); 8.04 74H, d,
Jˆ1.7 Hz); 8.05 74H, d, Jˆ1.7 Hz); 8.45 74H, s); 8.72 74H,
s); 8.92 74H, d, Jˆ5 Hz); 8.97 74H, d, Jˆ5 Hz).
M. R. J. thanks Central Queensland Universityfor the
provision of a Research Advancement Award and the
Australian Research Council for funding.
5.1.6. Bis-porphyrin cavity 15. Porphyrin BLOCK 3
722 mg, 16 mmol) and bis-epoxide 7 75 mg, 8.5 mmol)
were dissolved in CD2Cl2 7350 ml) and heated at 1408C
for 4 days followed by 1608C for 3 days. The solution was
taken to dryness and puri®ed by column chromatography
7silica) eluting with CHCl3/EtOAc 75%) yielding 15
734 mg, quantitative). Mp.3508C. ES-MS C218H240N16O14
7M1H)21 1655.5, M21 1654.5. UV 7DCM) l, 71£103): 424
7559.7), 456sh 7124.1), 537 726.4), 570sh 713.1), 609 721.5),
655 73.5). IR 7KBr): 1734.1, 1654 7CvO stretch), 1474.5,
7C±H deformation, Ar skeletal), 1362.2 7t-Bu C±H defor-
mation), 1290.1, 1245.9 7t-Bu skeletal), 1092.7 7C±O
stretch), 880.0 7Ar C±H out-of-plane), 799.7 7Ar-H, 2
adjacent H), 710.5 7cis-CHvCH, C±H stretch).
References
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